LOCAL SEISMIC RESPONSE AT SAN GIULIANO DI PUGLIA BY 1D, 2D AND 3D MODELS

The paper reports the comparison between 1D, 2D and 3D numerical simulations of seismic site response at San Giuliano di Puglia (Italy) and the amplification recorded in the aftershocks following the 31.X.2002 Molise earthquake (MW=5.7). The records were taken by mobile stations installed in the historical center on a soft rock outcrop and in the newer part of the town on a marly clay formation. The site response analyses by the 3D model involved a subsoil volume of about a 2000 x 2000 x 1500 m, including the extension of the whole town center at surface. 2D site response analyses were carried out on a section developing along the longitudinal axis of the town, and 1D simulations were referred to the subsoil profiles at the seismic stations. 1D and 2D models accounted for the heterogeneity of clayey formation, along both vertical and horizontal directions, as evidenced by a comprehensive geotechnical investigation. The results of numerical predictions are compared to the aftershocks records in terms of amplification functions and ground motion parameters (peak acceleration and Housner intensity)